Once again, I have several recordings of normal and pathological heart sounds.  However, the variety of pathological heart sounds that we can record in an undergraduate physiology teaching lab is extremely limited.  Below are some links to my favorite sites for listening to excellent examples of normal and pathological heart sounds.  If you have not yet gained familiarity with heart sounds, you may want to visit these sites and listen to some normal heart sounds.  Then, return here and read through the notes below on murmurs; that should give you a head start on interpretation of murmurs.  Remember, you cannot learn the significance of heart sounds by memorizing heart sounds... you learn the significance of heart sounds by understanding the events that are occurring in relation to the sounds that are being generated.  The hyperlinks provided are intended for your perusal and enjoyment only!  The material you are required to know is found below, beginning with the 4 sounds of Karotkoff!

The 4 "Heart Sounds of Karotkoff"

Before we get into the actual description of the sources of the "heart sounds of Karotkoff," we should recognize that Karotkoff identified as many as 17 heart sounds that may be of physiological origin!  Generally, we are only concerned with 4.  Should you choose to use an electronic stethoscope you will hear a phenomenal range of heart and vessel sounds.  Years ago, I used an electronic stethoscope (Medata) for determination of pregnancy in livestock.  I would use the stethoscope to listen for increased blood flow in the utero-ovarian artery.  When listening to the heart, not only could you hear distinctive blood flow patterns, but you could even hear the reverberation waves generated by the heart valves!  Phenomenal!  Certainly avail yourselves of the opportunity to use an electronic stethoscope if the opportunity ever presents itself!  Beyond this, I will give you the same advice that my cardiophysiology instructor gave me years ago; that is, i) you get better at detecting pathological heart sounds by listening to many hearts and then ii) placing pathological sounds as occurring between S1 and S2 or between S2 and S1 and then iii) trying to describe the nature of the sounds and relating the nature of the sound to ongoing changes in pressure in the heart.

So, where do we put the stethoscope?  Well, here is a suggested pattern!

1st heart sound (lub): As the ventricles contract, intra-ventricular pressure exceeds atrial pressure.  Along with contraction of the papillary muscles, increased intra-ventricular pressure snaps those AV valves tightly shut.  The AV valves are not blown backwards into the atria as they are attached to the papillary muscles by "chordae tendinae."  AV valve closure is the major component of the 1st heart sound (lub).  At the time of generation of S1, the ventricles are full (they contain the "end diastolic volume").

2nd heart sound (dup):  Now comes iso-volumetric ventricular contraction.  All heart valves are closed at the onset of ventricular contraction.  The semilunar valves of the aorta and pulmonary trunk will not open until intra-ventricular pressure exceeds arterial diastolic pressure.  That means that, in order for the left ventricle to open the aortic semilunar valve, left intra-ventricular pressure must exceed 80 mmHg, the diastolic pressure within the aorta!  In order for the right ventricle to open the pulmonary semilunar valve, right intra-ventricular pressure must exceed 8 mmHg, the diastolic pressure in the pulmonary trunk.  When intra-ventricular pressure exceeds arterial pressure, the semilunar valves "blow open" and blood is ejected from the ventricles.  Now begins the phase known as "the iso-volumetric ejection phase."  During the ejection phase, about 50% of the blood within the ventricles will be expelled during systole (end systolic volume = 75 ml).  At the end of ventricular systole, the ventricles relax and circumferential rebound of the stretched arterial walls pushes blood forward and backward, snapping the semilunar valves shut (dup).  This is the 2nd heart sound. The sharper sound of semilunar valve closure may be due to the high pressure which snaps them shut; this may be particularly true of the aortic semilunar valve.

3rd and 4th heart sounds: The 3rd and 4th heart sounds are very soft sounds and are normally very difficult to detect.  The major component of the 3rd heart sound (a swooshing sound) is a sudden rush of blood into the distended ventricles under central venous pressure in the first third of diastole ("passive ventricular filling" under central venous pressure).  The major component of the 4th heart sound (a spitting sound) is the rush of blood into the distended ventricles as the atria contract during the final third of diastole ("assisted ventricular filling" during atrial systole).  Please, please, please note... the 3rd and 4th heart sounds are not pathological sounds!  The 3rd and 4th heart sounds are normal transients.  But why do so many people call the 3rd and 4th heart sounds pathological?

When the 3rd and 4th heart sounds are "exaggerated," meaning they are louder than normal, and become much more easily heard, even with an inexpensive, non-cardiology stethoscope which can not normally detect the 3rd or 4th heart sounds, then the 3rd and 4th heart sounds are considered pathological.  That is, an exaggerated 3rd heart sound is pathological... for example, if you heard the 3rd heart sound as easily as you can hear the first or second heart sound, then certainly, that would be a significantly exaggerated 3rd heart sound which would be considered pathological.  If you are struggling to hear the 3rd or 4th heart sound, yet you are using a very high quality (eg. cardiology) stethoscope... then you are not hearing an "exaggerated 3rd or 4th heart sound, and you are not hearing a pathological heart sound.

Transients:  Transients are short duration sounds.  Transient sounds may be either normal or abnormal.  For example, S1 and S2 are transients which are normal.  Abnormal transients would include "systolic clicks" and "exaggerated" S3 and S4 or exaggerated ejection sounds.

"Systolic clicks" are metallic sounds heard between S1 and S2, which are generally to be considered of unknown origin.  These metallic clicks do not usually seem to be associated with pathologies.

A "protodiastolic gallop" is an exaggerated third heart sound.  Note that the word protodiastolic means very early diastole.  We know that the third heart sound is associated with passive ventricular filling under the influence of central venous pressure.  Hardening of the ventricles may lead to an exaggerated 3rd heart sound.  (pathological)

A "presystolic gallop" is an exaggerated fourth heart sound.  Note that the word presystolic refers to the last third of diastole (just before systole).  We know that the 4th heart sound is associated with active ventricular filling during atrial systole.  Again, hardened ventricular walls may lead to an exaggerated 4th heart sound (a presystolic gallop).  (pathological)

A "summation gallop" indicates that both the third and fourth heart sound are exaggerated.  (pathological)

"Exaggerated ejection sounds" are heard when ventricles eject blood into still distended arteries.  (sometimes normal, sometimes pathological)

Murmurs:  Murmurs are long duration sounds that result from turbulent flow around obstructions in the path of blood flow.  Unlike transients, all murmurs are considered pathological.  Murmurs are often classified as stenotic, insufficient, anemic, septal defect or patent ductus arteriosus.

We will look at murmurs below by superimposing "pictures" of murmurs over the ECG recording, just like in the diagram below.  Notice that on the line above the ECG tracing, we have added S1 and S2.  Remember, one of the first things you should do when you hear an abnormal sound, is determine whether the sound occurs between S1 and S2 or between S2 and S1.

Valvular murmurs:

Stenosis:  A stenosis means that the valve is partially occluded (blocked or restricted) when it is open.

Insufficiency:  An insufficiency means that a valve leaks when it is closed.

AV valve stenosis:  This is a rare murmur.  The murmur would be heard between S2 and S1 as it is caused by partial occulsion/ blockage of one of the AV valves.  Remember that the greatest rates of ventricular filling occur during the 1st third and the last third of diastole.  That means that the murmur is noisiest during the 1st third of diastole, gradually decreasing throughout diastasis and then increases again during atrial systole.  The murmur is sometimes described as decrescendo-acrescendo (getting quieter then louder).  Sometimes the portion of the murmur heard during atrial systole is described as "presystolic graduation."  We might picture it this way!  The width of the blue bar is intended to depict the intensity of the murmur!

AV valve insufficiency:  An insufficiency of the mitral valve (bicuspid or left AV valve) is common!  This murmur would be heard during systole.  Because the sound is fairly consistent throughout systole, the murmur is described as "holosystolic."  Remember that an insufficiency means a leaky valve.  If the AV valve leaks, it will do so when it is tested by the highest pressures, and that is during systole, between S1 and S2.  Here, you should picture some blood squirting back into the atria because of the high intraventricular pressure!  We might picture the murmur like this!

Semilunar valve stenosis:  Another rare murmur, a semilunar stenosis would again be heard during systole, S1 and S2.  This murmur is described as graduating through the 1st half of systole and decrescendo through the second half of systole.  An alternate description is acrescendo-decrescendo or "diamond" shape, because it looks like a diamond when we sketch the murmur based on sound intensity.  A pictograph of the murmur might look like this:

Oh, just a bit of trivia for you dog owners out there... semilunar stenoses are often associated with heart worms!  Makes sense, right... masses of worms block the valve openings.

Semilunar Valve Insufficiency:  This uncommonly detected murmur is heard during circumferential rebound of the large arteries, as high arterial pressure pushes blood back through the leaky semilunar valve into the distended (relaxed) ventricles.  This sound obviously occurs during diastole, between S2 and S1.  The murmur begins immediately upon closure of the semilunar valves and continues to decline throughout diastole with the decline in arterial pressure from systolic to diastolic pressure!  The murmur might be pictured like this:

The Non-Valvular Murmurs Page!

Many common murmurs are non-valvular:

Anemia-associated murmur:  This high pitched murmur is associated with increased blood flow during systole!  The murmur is described as decrescendo in the first half of systole and whispy in the 2nd half of systole.  A pictograph of the murmur might look like this:

Ventricular septal defect:  A ventricular septal defect is associated with a "holosystolic" murmur heard during systole.  This murmur varies in pitch and for this reason is sometimes described as "rough."  The murmur that is heard because of a septal defect might be pictured like this:

Patent Ductus Arteriosus:  Here, the arterio-venous shunt (fistula) results in a "continuous machinery murmur," with graduation (acrescendo) from S1 to S2, and decrescendo from S2 to S1.